MPSC 2025 Prelims Paper-I · Question 34 of 100

Correct — option (4), Geothermal energy, is a renewable energy resource. It draws on the heat continuously generated deep within the Earth by the natural radioactive decay of minerals in the core and mantle, a heat source that is effectively inexhaustible on any human timescale and is continuously replenished rather than drawn down like a stock of buried fuel. This heat can be tapped wherever it reaches close enough to the surface — through hot springs, geysers, or engineered wells into hot rock — to generate electricity or provide direct heating, without consuming a finite deposit in the process. That renewability, driven by an ongoing planetary heat-generation process rather than the slow geological accumulation of ancient organic matter, is exactly what separates geothermal energy from the other three options, all of which are fossil fuels.

• (1)Rock-Coal — Coal is a fossil fuel, formed over millions of years from the compression and chemical alteration of ancient plant matter under heat and pressure. Because it takes geological timescales to form, any coal extracted and burned today is effectively gone for good within a human lifetime — it is a stock resource that is depleted with use, which makes it non-renewable, not renewable.
• (2)Mineral Oil/Petroleum — Petroleum is likewise a fossil fuel, formed from the remains of ancient marine organisms buried and transformed over millions of years under heat and pressure. Like coal, it exists in a fixed, finite geological stock that is consumed and not replenished on any timescale relevant to human energy planning, making it a classic non-renewable resource rather than a renewable one.
• (3)Natural Gas — Natural gas is also a fossil fuel, formed alongside coal and petroleum through the same slow geological processes acting on buried organic matter over millions of years. Despite being cleaner-burning than coal or oil, it is extracted from a finite underground reserve and is not naturally replenished at any pace that matters for renewability, so it belongs with the other fossil fuels as a non-renewable resource.

Energy resources are classified as renewable or non-renewable based on the rate at which nature replenishes them relative to the rate humans consume them. Renewable resources — solar, wind, hydro, geothermal, tidal, biomass — are continuously or rapidly regenerated by ongoing natural processes and are not depleted by use in any meaningful human timescale. Non-renewable resources — coal, petroleum, natural gas, and nuclear fuel minerals — exist as finite geological stocks laid down over millions of years, and every unit consumed reduces the remaining stock permanently. Geothermal energy is renewable specifically because its source, the Earth's internal heat from radioactive decay, is continuously generated rather than being a fixed deposit of ancient organic matter.

MPSC and UPSC both test this classification repeatedly because it underpins a large share of environment and economy questions on energy policy, and the trap in this particular item is that three of the four options are fossil fuels that differ from each other in origin, composition and use, which can distract a candidate from noticing that the actual distinguishing test — replenishment rate versus depletion — sorts all three onto the same non-renewable side, leaving geothermal energy as the clear outlier.

• Geothermal energy is renewable: it draws on heat continuously generated by radioactive decay deep within the Earth, which is not depleted by use.
• Coal, petroleum and natural gas are all fossil fuels, formed over millions of years from buried organic matter under heat and pressure.
• Fossil fuels are non-renewable because they exist as finite geological stocks that are consumed faster than nature can replenish them.
• The standard set of renewable resources includes solar, wind, hydro, geothermal, tidal and biomass energy.
• Renewability is defined by replenishment rate relative to human consumption, not by how 'clean' a fuel is when burned — natural gas is cleaner-burning than coal but is still non-renewable.

• Assuming natural gas is renewable because it burns cleaner than coal or oil, when cleanliness of combustion has nothing to do with whether the resource is replenished
• Treating all 'earth-derived' energy sources as similar, without separating fossil fuels (finite, depleting) from geothermal heat (continuously generated)
• Overlooking geothermal energy as a renewable option because it is less commonly discussed in Indian media than solar or wind

MPSC's Paper-I environment and economy sections regularly test the renewable-versus-non-renewable classification as direct recall, usually by mixing one renewable option among three fossil fuels exactly as in this question. The safest preparation is to fix the standard renewable list (solar, wind, hydro, geothermal, tidal, biomass) and the standard fossil-fuel list (coal, petroleum, natural gas) side by side, since examiners rarely test any resource outside these two familiar sets.

No directly related past PYQ was found.

• practice — not a real PYQ

  Geothermal energy is classified as a renewable energy resource primarily because its source is which of the following ?

  • (a)Solar radiation stored in rock formations
  • (b)Heat continuously generated by radioactive decay within the Earth
  • (c)Compressed ancient organic matter
  • (d)Tidal forces acting on coastal rock

  Answer(b) Heat continuously generated by radioactive decay within the Earth — this ongoing internal heat-generation process, rather than a fixed geological deposit, is what makes geothermal energy renewable.

• practice — not a real PYQ

  Which of the following is NOT a fossil fuel ?

  • (a)Coal
  • (b)Natural gas
  • (c)Geothermal energy
  • (d)Petroleum

  Answer(c) Geothermal energy — unlike coal, natural gas and petroleum, it is not formed from buried ancient organic matter and is not a finite, depleting stock resource.